1158 



A MANUAL OF ANATOMY 



nerves of the lower group usually exceed those of the upper in 

 number. As they pass forward above and below the optic nerve 

 they divide, and give rise to from sixteen to twenty delicate 

 filaments. Having reached .the back of the eyeball, they pierce the 

 sclerotic around the entrance of the optic nerve. They then pass 

 forwards between the sclerotic and the choroid, giving twigs to the 

 latter, and they are finally distributed to the ciliary muscle, the iris, 

 and the cornea. The short ciliary nerves thus convey to the 

 eyeball sensory fibres from the ophthalmic division of the fifth 

 nerve, motor fibres from the third nerve, and sympathetic fibres 

 from the cavernous plexus of the sympathetic. 



Frontal Artery Internal Palpebral Arteries 



Nasal Artery 



Trochlea of Superior Oblique 



Anterior Ethmoidal Artery, 



Posterior Ethmoidal Artery Jffl 



Arteria Centralis Retinae 



(in outline) ' Y;|\ 



Superior Oblique AIJ 



Superior Rectus (cut). 



Levator Palpebrje Superioris (cut). 



Optic Nerve -,^ 



Optic Commissure (right half) — 



Lachrymal Gland 



-^ Jl — Supra-orbital Artery 



External Ciliary Arteries 

 Lachrymal Artery 

 External Rectus (cut) 

 Ophthalmic Artery 



Right Optic Tract 



Fig. 472. — Dissection of the Right Orbit from above, showing the 

 Optic Nerve, Ophthalmic Artery, and Superior Oblique Muscle. 



Summary of the Ophthalmic Nerve. — This nerve is entirely sensory. It 

 supplies (i ) the skin of (a) the frontal region and top of the skull, (b) the upper 

 eyelid, and (c) the root, tip, and lower part of the side of the nose ; (2) the 

 caruncula lacrimalis and lachrymal sac ; (3) the mucous membrane of the 

 nasal fossa, and the palpebral conjunctiva; (4) the eyeball; and (5) the 

 lachrymal gland. 



Summary of the Ciliary Ganglion. — The branches of this ganglion supply the 

 cornea, iris, and ciliary muscle. The fibres which supply the sphincter 

 pupillSB are derived from the third or oculo-motor nerve, through means of 

 the motor root of the ganglion. The fibres which supply the dilator pupillse 

 are derived from the sympafhetic, through means of the sympathetic root 

 of the ganglion, which is derived from the cavernous sympathetic plexus. 



Branch of the Superior Maxillary Division of the Fifth. — The 

 orbital or temporo-malar nerve, of small size, arises from the superior 

 maxillary in the spheno-maxillary fossa. It enters the orbit 

 through the spheno-maxjllary fissure, and soon divides into two 



